1. Field
The invention relates to a controlled method of crystal growth and specifically to a system of monitoring in-situ the solid-liquid interface of a growing crystal and of providing feedback control means for controlling parameters of various crystal growth processes, such as furnace temperature profile and movement of a growth material ampoule, to produce high quality crystals, with the growth process presented herein as growing compound crystal materials using a modified vertical Bridgman method.
2. Prior Art
Melt growth is one of the most popular methods for growing large crystals of infrared (IR) materials. This method can be accomplished by directional solidification of the molten material by normal freezing or zone melting. Normal freezing can be carried out in several ways with the Bridgman method being one of those widely practiced. Bridgman growth is accomplished by progressive movement of the solid-liquid interface in a controlled manner. It is known that the shape of the solid-liquid interface during solidification affects the compositional homogenity, dislocation density, and mechanical properties of the crystals. Studies to correlate the solid-liquid interface and the properties of resulting crystals exist on very few materials. Even the studies that were made were carried out after the growth. The growth mechanism and the origin of defects are difficult or impossible to analyze without an observation of the solid-liquid interface at the time of the growth process.
A solution to this problem is made possible by the present system for in-situ visualization of a solid-liquid interface during the crystal growth process.